Ampere's law, Biot-Savart law and E-field questions

Hi,
1. Generally when using Gauss's law to e-field, i'm aware that the the surface you chose must be symmetrical and E-field is constant therefore you would only use Gauss's law for infinite sheets of charge, spherical distribution of charge and infinite line charge am i right?

2. Regarding ampere's law, i'm aware that we use this when the B-field is constant does this only the direction is not changing? (eg. for a circular loop it will always point in the (phi) direction). A follow up on this question, for a square loop how does the b-field look like.

3. Lastly, we would use biot-savart law over amperes law in any case we aren't dealing with a current carrying wire, am i right?

I have an exam next week on this stuff, and i just want to make sure i have the theory right because that's what i'm confused about, the calculus bit will easily fall in place once the theory is clear. Thank you for any help.